Multi-station debris separation system

ABSTRACT

The present disclosure generally relates to separating solid particles from an airflow in a gas turbine engine. A system for separating debris includes a first separation device in fluid communication with an inlet flow path of a compressor and a second separation device in fluid communication with an outlet flow path of the compressor and an inlet flow path of a combustor. The first separation device is adapted to remove coarse particles from the airflow. The second separation device is adapted to remove fine particles from the airflow. The course particles have a larger mean particle diameter than the fine particles.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. Non-provisional patentapplication Ser. No. 15/215,353, entitled “Multi-Station DebrisSeparation System,” filed Jul. 20, 2016, the contents of which as herebyincorporated by reference in their entirety.

INTRODUCTION

The present disclosure generally relates to debris separation in a gasturbine engine.

BACKGROUND

In a gas turbine engine, intake air is compressed by a compressor. Fuelis added to the compressed air and ignited in a combustor. The expandinghot air passes through a turbine and out of a nozzle providing thrust.The turbine converts some of the energy of the expanding hot air intorotational energy for powering the compressor.

Various components of a gas turbine engine may be damaged and/ordegraded when the intake air contains particles such as sand and dust.For example, sand may cause abrasion to compressor blades. As anotherexample, dust may clog cooling holes and/or reduce cooling performancein the turbine resulting in higher turbine temperatures. The damage tothe engine components reduces the efficiency and lifespan of the engine.

Debris removal systems for gas turbine engines generally attempt toremove all types of debris from the intake air using a single separator.While a single separator may reduce the total amount of debris enteringthe components of the gas turbine engine, a single separator may notefficiently remove different types of debris. For example, if the singleseparator is optimized for removing large particles, small particles maypass through the compressor to the combustor and turbine. On the otherhand, if the single separator is optimized for removing smallerparticles, large particles may pass through the compressor, damaging thecompressor. Further, the compressor may pulverize larger particles intosmaller particles that may also damage the turbine.

In view of the above, it can be appreciated that there are problems,shortcomings or disadvantages associated with debris separation in gasturbine engines, and that it would be desirable if improved systems andmethods for separating debris from an airflow in a gas turbine enginewere devised.

SUMMARY

The following presents a simplified summary of one or more aspects ofthe invention in order to provide a basic understanding of such aspects.This summary is not an extensive overview of all contemplated aspects,and is intended to neither identify key or critical elements of allaspects nor delineate the scope of any or all aspects. Its purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

In one aspect, the disclosure provides a system for separating debrisfrom an airflow in a gas turbine engine. The system includes a firstseparation device in fluid communication with an inlet flow path of acompressor. The first separation device adapted to remove coarseparticles from the airflow. The system also includes a second separationdevice in fluid communication with an outlet flow path of the compressorand an inlet flow path of a combustor. The second separation device isadapted to remove fine particles from the airflow. The course particleshave a larger mean particle diameter than the fine particles.

In another aspect, the disclosure provides a gas turbine engine. The gasturbine engine includes a first separation device that receives ambientair including entrained solid particles and removes at least 80 percentof the solid particles having a mean particle diameter between 80micrometers and 1000 micrometers from the ambient air. The gas turbineengine also includes a compressor that receives the ambient air from thefirst separation device and generates compressed air. The gas turbineengine further includes a second separation device that receivescompressed air from the compressor including entrained solid particleshaving a mean particle diameter less than 5 micrometers and removes atleast 70 percent of the entrained solid particles from the compressedair.

In another aspect, the disclosure provides a method of removing solidparticles from an airflow in a gas turbine engine including a compressorand a combustor. The method includes receiving ambient air includingentrained solid particles. The method further includes removing at least80 percent of the entrained solid particles having a mean particlediameter between 80 micrometers and 1000 micrometers from the ambientair before the compressor. The method also includes compressing theambient air in the compressor to generate compressed air includingentrained solid particles having a mean particle diameter less than 5micrometers. The method additionally includes removing at least 80percent of the entrained solid particles from the compressed air beforethe combustor.

These and other aspects of the invention will become more fullyunderstood upon a review of the detailed description, which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a side section view of aspects ofa conventional gas turbine engine.

FIG. 2 is a diagram illustrating an example classification of debrisparticle sizes.

FIG. 3 is a schematic diagram of an exemplary gas turbine engine with amulti-station debris separation system.

FIG. 4 is a side section view of an exemplary inlet particle separator.

FIG. 5 is a side section view of an exemplary multi-stage particleseparator.

FIG. 6 is a side section view showing flowpaths within the exemplarymulti-stage particle separator of FIG. 5.

FIG. 7 is a perspective view of a cyclonic separator.

FIG. 8 is an axial cross-sectional view of the cyclonic separator inFIG. 7.

FIG. 9 is transverse cross-sectional view of the cyclonic separator inFIG. 7.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known components are shown in blockdiagram form in order to avoid obscuring such concepts.

This written description uses examples to disclose the invention,including the preferred embodiments, and also to enable any personskilled in the art to practice the invention, including making and usingany devices or systems and performing any incorporated methods. Thepatentable scope of the invention is defined by the claims, and mayinclude other examples that occur to those skilled in the art. Suchother examples are intended to be within the scope of the claims if theyhave structural elements that do not differ from the literal language ofthe claims, or if they include equivalent structural elements withinsubstantial differences from the literal language of the claims.Aspects from the various embodiments described, as well as other knownequivalents for each such aspect, can be mixed and matched by one ofordinary skill in the art to construct additional embodiments andtechniques in accordance with principles of this application.

As used herein, the terms “axial” or “axially” refer to a dimensionalong a longitudinal axis of an engine. The term “forward” used inconjunction with “axial” or “axially” refers to moving in a directiontoward the engine inlet, or a component being relatively closer to theengine inlet as compared to another component. The term “aft” used inconjunction with “axial” or “axially” refers to moving in a directiontoward the rear or outlet of the engine, or a component being relativelycloser to the outlet than the inlet.

As used herein, the terms “radial” or “radially” refer to a dimensionextending between a center longitudinal axis of the engine and an outerengine circumference. The use of the terms “proximal” or “proximally,”either by themselves or in conjunction with the terms “radial” or“radially,” refers to moving in a direction toward the centerlongitudinal axis, or a component being relatively closer to the centerlongitudinal axis as compared to another component. The use of the terms“distal” or “distally,” either by themselves or in conjunction with theterms “radial” or “radially,” refers to moving in a direction toward theouter engine circumference, or a component being relatively closer tothe outer engine circumference as compared to another component. As usedherein, the terms “lateral” or “laterally” refer to a dimension that isperpendicular to both the axial and radial dimensions.

FIG. 1 is a schematic cross-sectional diagram of a gas turbine engine 10for an aircraft. The engine 10 has a generally longitudinally extendingaxis or centerline 12 extending forward 14 to aft 16. The engine 10includes, in downstream serial flow relationship, a compressor section22 including a booster or low pressure (LP) compressor 24 and a highpressure (HP) compressor 26, a combustion section 28 including acombustor 30, a turbine section 32 including a HP turbine 34, and a LPturbine 36, and an exhaust section 38. The HP compressor 26, thecombustor 30, and the HP turbine 34 form a core 44 of the engine 10,which generates combustion gases. The core casing 46 surrounds the core44.

A HP shaft or spool 48 disposed coaxially about the centerline 12 of theengine 10 drivingly connects the HP turbine 34 to the HP compressor 26.A LP shaft or spool 50, which is disposed coaxially about the centerline12 of the engine 10 within the larger diameter annular HP spool 48,drivingly connects the LP turbine 36 to the LP compressor 24. Theportions of the engine 10 mounted to and rotating with either or both ofthe spools 48, 50 are referred to individually or collectively as arotor 51.

The LP compressor 24 and the HP compressor 26 respectively include aplurality of compressor stages 52, 54, in which a set of compressorblades 58 rotate relative to a corresponding set of static compressorvanes 60, 62 (also called a nozzle) to compress or pressurize the streamof fluid passing through the stage. In a single compressor stage 52, 54,multiple compressor blades 56, 58 can be provided in a ring and canextend radially outwardly relative to the centerline 12, from a bladeplatform to a blade tip, while the corresponding static compressor vanes60, 62 are positioned downstream of and adjacent to the rotating blades56, 58. It is noted that the number of blades, vanes, and compressorstages shown in FIG. 1 were selected for illustrative purposes only, andthat other numbers are possible. The blades 56, 58 for a stage of thecompressor can mount to a disk 53, which mounts to the corresponding oneof the HP and LP spools 48, 50, with each stage having its own disk. Thevanes 60, 62 mount to the core casing 46 in a circumferentialarrangement about the rotor 51.

The HP turbine 34 and the LP turbine 36 respectively include a pluralityof turbine stages 64, 66, in which a set of turbine blades 68, 70 arerotated relative to a corresponding set of static turbine vanes 72, 74(also called a nozzle) to extract energy from the stream of fluidpassing through the stage. In a single turbine stage 64, 66, multipleturbine blades 68, 70 can be provided in a ring and can extend radiallyoutwardly relative to the centerline 12, from a blade platform to ablade tip, while the corresponding static turbine vanes 72, 74 arepositioned upstream of and adjacent to the rotating blades 68, 70. It isnoted that the number of blades, vanes, and turbine stages shown in FIG.1 were selected for illustrative purposes only, and that other numbersare possible.

In operation, air is supplied to the LP compressor 24, which thensupplies pressurized ambient air to the HP compressor 26, which furtherpressurizes the ambient air. The pressurized air from the HP compressor26 is mixed with fuel in the combustor 30 and ignited, therebygenerating combustion gases. Some work is extracted from these gases bythe HP turbine 34, which drives the HP compressor 26. The combustiongases are discharged into the LP turbine 36, which extracts additionalwork to drive the LP compressor 24, and the exhaust gas is ultimatelydischarged from the engine 10 via the exhaust section 38. The driving ofthe LP turbine 36 drives the LP spool 50 to rotate the LP compressor 24.

Some of the ambient air can bypass the engine core 44 and be used forcooling of portions, especially hot portions, of the engine 10, and/orused to cool or power other aspects of the aircraft. In the context of aturbine engine, the hot portions of the engine are normally downstreamof the combustor 30, especially the turbine section 32, with the HPturbine 34 being the hottest portion as it is directly downstream of thecombustion section 28. Other sources of cooling fluid can be, but is notlimited to, fluid discharged from the LP compressor 24 or the HPcompressor 26.

FIG. 2 is a diagram 200 illustrating an example classification of debrisparticle sizes. The diagram 200 illustrates three classifications ofparticle size, coarse particles 210, fine particles 220, and superfineparticles 230. The coarse particles 210 generally have a mean particlediameter smaller than 1000 micrometers (microns or μm) and generallylarger than 80 μm. The coarse particles 210 may be, for example, sand.The fine particles 220 generally have a mean particle diameter smallerthan 80 μm and generally larger than 5 μm. The superfine particles 230generally have a mean particle diameter smaller than 5 μm. In an aspect,the term “fine” may be used to describe both fine particles 220 andsuperfine particles 230. The different particle sizes may behavedifferently within an airflow in a gas turbine engine, have differenteffects in a gas turbine engine, and damage different components of thegas turbine engine. For example, the behavior of coarse particles 210 isdominated by particle momentum. That is, the coarse particles 210 tendto travel in a line. The behavior of fine particles 220, however, may bedominated by centrifugal force. For example, fine particles may bepulled to the outside of the gas turbine engine as an air flow swirls.In contrast, the behavior of superfine particles 230 is dominated bydrag force. For example, superfine particles 230 travel with the airflowand may stick to surfaces of the gas turbine engine. Coarse particles210 tend to damage compressor rotor assemblies and impellers. Inparticular, the coarse particles 210 cause burrs and rollover on theleading edge of impellers and also round the tips as the coarseparticles 210 abrade the spinning parts. Superfine particles 230 tend toaccumulate on or within the combustor 30 or the turbine 34, 36. Forexample, superfine particles 230 may accumulate within cooling holes ofthe turbine blades and eventually block the cooling holes, leading to arise in turbine temperature.

FIG. 3 is a cross-section of the gas turbine engine 10 with amulti-station debris separation system including an inlet particleseparator 88 and a multi-stage separator 340. The cross-section of thegas turbine engine 10 illustrates an inlet section 80 and a conduitsection 82 in axial arrangement upstream of the compressor section 22,and an outlet section 84 downstream of the turbine section 32. The inletsection 80 has an inlet particle separator 88 having an inlet 90, acenterbody 92, and a scavenge plenum 98. Depending on the configurationof the gas turbine engine 10, the inlet section 80 receives an inletairflow of ambient air which may be directed into the inlet section 80by a fan or prop (not shown) powered by the HP spool 48 or LP spool 50.The inlet section 80 includes a rim 332 separating the inlet air flow tothe core 44 from a bypass air flow outside of the core 44. The inletparticle separator 88 is positioned radially distal to the rim 332. Aswill be described in further detail below with respect to FIG. 4, theinlet particle separator 88 is adapted to separate coarser particlesfrom the inlet airflow. Inlet particle separator 88 is in fluidcommunication with the compressor section 22 and coarser particles mayabrade the blades 58 of the compressor section 22.

The inlet 90 defines an opening for providing a flow of air to thedownstream sections. Axially downstream of the inlet 90 is thecenterbody 92 having an impact surface 94 formed by a portion of thecenterbody 92, confronting a flow of air provided from the inlet 90. Aninlet duct 96 is defined about the centerbody 92 and radially, outwardlybounded by the scavenge plenum 98 in fluid communication with the inletduct 96. One or more plenum inlets 100 provide fluid communicationbetween the inlet duct 96 and the scavenge plenum 98. The inlet 90,centerbody 92, and the scavenge plenum 98 are all annular, such that theinlet duct 96 is radially defined around the engine centerline 12. It iscontemplated that the scavenge plenum 98 can alternatively compriseother scrolls, scavenge conduits, or can be a combination of multiplescavenge conduits arranged radially about the engine centerline 12.

The conduit section 82 has a flow conduit 102 fluidly coupling the inletduct 96 to the compressor section 22 of the engine 10. The flow of airprovided to the inlet 90 can pass around the centerbody 92 through theinlet duct 96 and to the flow conduit 102, providing air to thecompressor section 22. The outlet section 84 has one or more struts 104arranged radially around the engine centerline 12.

Turning to FIG. 4, an exploded view of the inlet particle separator 88,best illustrating the combination of the components for providing anairflow to the engine core 44. A front plate 120 mounts to a scavengeconduit 122, defining the scavenge plenum 98. The front plate 120 andcenterbody 92 for the radially outward flowing inlet to the turn 96.Particles are accelerated in a radially outward direction for scavengingthrough the plenum inlets 100. The scavenge conduit 122 has a scavengeoutlet 124 for providing a scavenge flow of air overboard. Radiallywithin the scavenge conduit 122 is the centerbody 92. A scavenge inletsection 126 can comprise a plurality of annular scavenge vanes 128mounted to one or more bands 130 to define the plenum inlets 100 of FIG.3. The scavenge vanes 128 comprise wedge-shaped bodies oriented todefine a radial disposition of the plenum inlets 100 is radial.Alternatively, it is contemplated that the scavenge vanes 128 can be anyshape, such that the wedge-shape is non-limiting. Furthermore, thedisposition of the scavenge vanes 128 can define an axial orientationfor the plenum inlets 100. While four scavenge vanes 128 are shown, anynumber of scavenge vanes 128 is contemplated to define any number ofplenum inlets 100. An inner member 132 and an outer member 134 candefine the radially inner and outer bounds of the flow conduit 102axially downstream of the centerbody 92. The centerbody 92 and the innermember can couple in axial arrangement, being supported within the outerarrangement of the scavenge conduit 122 and the scavenge inlet section126.

The structural elements of the inlet particle separator 88 are easilyinterconnectable to form the inlet particle separator 88. The inletparticle separator 88 can be mechanically removable from the conduitsection 82. Installation and maintenance of the inlet section 80 isfacilitated with easy of removability. It should be understood, however,that differing manufacturing combinations are possible to develop theapparatus disclosed herein. Further details of the inlet particleseparator 88 and operation thereof are described in copending U.S.application Ser. No. 15/002,839, filed Jan. 21, 2016, titled “INLETPARTICLE SEPARATOR FOR A TURBINE ENGINE,” which is incorporated hereinby reference in its entirety.

The inlet particle separator 88 is designed to remove larger particleswhose separation force is dominated by particle momentum, and to alesser degree centrifugal forces. The inlet separator removes at least80%, and preferably 95% or more, of the coarse particles (80-100microns) from the inlet airstream. The inlet separator removes at least70%, preferably 80% or more, of the fine particles (5-80 microns) fromthe inlet stream. The inlet separator removes approximately 50% of thesuperfine material. Because of the overall design of the system, removalof superfine material at this stage is not critical. The remainder ofthe coarse and fine material passing through the compressor section 22is generally pulverized into fine and superfine material resulting in anaddition of particulate superfines on top of what was not removed at theinlet particle separator 88.

The multi-stage separator 340 is located downstream from the compressorsection 22, which compresses the inlet air flow and provides acompressed air flow. The compressor section 22 also pulverizes largerparticles remaining within the input airflow after the inlet particleseparator 88 into smaller particles (e.g., superfine particles). Themulti-stage separator 340 includes one or more separators that bleed aportion of the compressed airflow for various uses. For example, themulti-stage separator 340 includes a cyclonic separator 342 and a cleanair offtake 344. In an aspect, the multi-stage separator 340 is adaptedto remove smaller particles (e.g., fine and superfine particles) fromthe compressed airflow. The multi-stage separator 340 will be describedin further detail below with respect to FIGS. 5 and 6. The multi-stageseparator 340 is designed to remove fine and superfine particulatepassing through the compressor. Preferably at least 70%, more preferably80%, of the remaining material is removed at this stage.

FIG. 5 is a side section view of the multi-stage separator 340. Themulti-stage separator 340 receives a compressed air flow from thecompressor 314. In particular, the compressor impeller 510 is a laststage of the compressor section 22. As illustrated, the compressorimpeller 510 is a centripetal impeller that further compresses theairflow and pushes the air in a radially distal direction against animpeller shroud 514. The impeller shroud 514 defines a portion of theflowpath having a reduced cross-section. As the compressed airflowleaves the compressor impeller 510, the airflow accelerates. Thecompressor impeller 510 and the impeller shroud 514 also turn theairflow in a radial distal direction. A compressor case 518 supports theimpeller shroud 514 and also defines a space outside of the mainflowpath between the compressor case 518 and the impeller shroud 514.

The multi-stage separator 340 includes a cyclonic separator 520, adiffuser 530, a clean air offtake 540, an optional heat exchanger 550,and a deswirler 560. The cyclonic separator 520 includes an intake 516located along a radially distal surface of the impeller shroud 514. Theradially distal surface defines a surface of the flowpath as thecompressor impeller 510 turns the airflow in the radially distaldirection. The intake 516 for example, includes a cowl having a at leastone opening within the radially distal surface of the impeller shroud514. For example, the at least one opening may be a continuous slit or aplurality of openings. Because the solid particles entrained within thecompressed airflow 504 are mostly superfine particles 230, the dragforce tends to dominate, and the particles concentrate along theradially distal surface of the impeller shroud 514. A portion of thecompressed airflow enters the cyclonic separator 520 via the pluralityof openings, carrying the solid particles into the cyclonic separator520.

In an embodiment, the cyclonic separator 520 includes a plurality ofcyclonic chambers surrounding the impeller shroud 514. The cyclonicseparator 520 is adapted for separating superfine particles because thedrag force causes superfine particles to remain in an outer vortex whilerelatively clean air can be extracted from an inner vortex. Therelatively clean air exits through an outlet to form a clean airflowwhile the solid particles are collected in a collection chamber. Thecollection chamber is a sealable collection chamber that is sealedduring operation of the gas turbine engine 300. Accordingly, thecompressed airflow 504 does not lose pressure to a vent. The collectionchamber is vented during a shutdown, cleaning, or startup operation. Forexample, the collection chamber is vented when an air starter is used tostart the gas turbine engine 300.

The diffuser 530 conveys a first remaining portion of the compressedairflow 504 in the radially distal direction towards a deswirler 560.The diffuser 530 is supported by the diffuser case 524. The diffusercase 524 and the diffuser 530 define a flowpath for a cleaned airflowfrom the cyclonic separator 520. In other words, the cleaned air fromthe cyclonic separator 520 flows within the diffuser case 524 withoutreentering the primary airflow within the diffuser 530. Ducts orpassages between walls of a multi-walled component (e.g., the deswirler560) route the cleaned airflow to an optional heat exchanger 550 anddownstream cooling and/or pressurization uses.

The deswirler 560 is located about a radially distal edge of thediffuser 530. The deswirler 560 turns the airflow in an axially aftdirection and reduces lateral movement of the airflow. A radially distalsurface of the deswirler 560 is defined in part by an engine mount 552that forms a radially distal wall of the gas turbine engine 300. Theclean air offtake 540 is located at a radially proximal surface of thedeswirler 560. For example, the clean air offtake 540 includes anopening within the radially proximal surface of the deswirler 560forming an inlet to the clean air offtake 540. Due to centrifugal forceand drag forces, the remaining solid particles entrained within theprimary airflow tend to drag along the radially distal surface of thediffuser 530 and the engine mount 552. Accordingly, the clean airofftake 540 separates a portion of relatively clean air from thecompressed primary airflow. In an aspect, the clean air offtake 540further includes a deflector partially covering the inlet to the cleanair offtake 540. The deflector deflects solid particles away from theinlet to the clean air offtake 540 to provide a cleaner airflow withinthe clean air offtake 540.

The clean air offtake 540 also includes ducts or passages that form asecondary flowpath to an optional heat exchanger 550 and downstreamcooling uses. A remaining portion of the compressed primary airflowtravels through the deswirler 560 into the combustor 316.

The optional heat exchanger 550 cools one or more cleaned airflows. Forexample, the heat exchanger 550 is in fluid communication with thecyclonic separator 520 or the clean air offtake 540. The heat exchanger550 includes separate flowpaths for the one or more cleaned airflows andfor a relatively dirty waste airflow. For example, the waste airflow maybe a bypass airflow or ambient air. The cleaned airflows may be a firstcleaned airflow from the cyclonic separator 520 or a second cleanedairflow from the clean air offtake 540. Heat from the cleaned air flows,which are compressed, is transferred into the dirty airflow, which isthen vented.

FIG. 6 is a side section view showing airflows within the exemplarymulti-stage separator 340. The compressor 314 provides a compressedairflow 504 from the compressor impeller 512 towards the impeller shroud514, where the cyclonic separator 520 bleeds of a portion of thecompressed airflow 504 and produces a first cleaned airflow 610. Aremaining portion of the compressed airflow 504 travels through thediffuser 530 until the clean air offtake 540 bleeds off a second cleanedairflow 620. The remaining portion of the compressed airflow 504 becomesthe flowpath airflow 630, which flows to the combustor 316. The flowpathairflow 630 enters the combustor 316 via a fuel nozzle 640, where theflowpath airflow 630 is mixed with fuel and ignited. The flowpathairflow 630 also enters the combustor 316 via openings in the combustorliner 642.

The second cleaned airflow 620 may be the cleanest airflow. For example,the second cleaned airflow 620 may have a lower concentration of solidparticles than the compressed airflow 504, the first cleaned airflow610, or the flowpath airflow 630. The second cleaned airflow 620 may beused to cool a first stage of a high pressure turbine 320. The secondcleaned airflow 620 flows through an optional heat exchanger 550 on itsway to the high pressure turbine 320. Ducts or passages within themulti-walled components of the gas turbine engine 300 route the secondcleaned airflow 620 to an accelerator 564. The second cleaned airflow620 is passed from the accelerator 564 through the turbine blades viacooling holes and provides for thin film cooling of the turbine blades.

The first cleaned airflow 610 is routed to a second stage of the highpressure turbine 320. The first cleaned airflow 610 may be of lowerpressure than the second cleaned airflow 620. Ducts or passages withinthe multi-walled components of the gas turbine engine 300 route thefirst cleaned airflow 610 to the second stage of the high pressureturbine via an outer shell of the combustor 216 and via a bearing sump566. The second stage of the high pressure turbine 320 may operate at alower temperature than the first stage of the high pressure turbine andbe less susceptible to damage from solid particles.

FIG. 7 is a perspective view of a cyclonic separator 700. The cyclonicseparator 700 is an example of the cyclonic separator 520. It should beappreciated, however, that a cyclonic separator 700 may be located in adifferent position within the core 302. For example, the cyclonicseparator 700 may be located before the compressor 314. The cyclonicseparator 700 includes a cowl 710 including a plurality of openings 720in fluid communication with a plurality of vortex chambers 740. A rim730 defines an end of the cowl 710. The vortex chambers 740 are in fluidcommunication with a collection chamber 750, which also defines a bodyof the cyclonic separator 700. A flange 760 is connected to thecollection chamber 750 to provide structural support and attachmentpoints for the cyclonic separator 700.

The cowl 710 defines radially distal surface of a flowpath within thecore 302. In an embodiment, the cowl 710 is the radially distal surfaceof the impeller shroud 514. That is, the cowl 710 helps restrict theflowpath of the compressed air from the compressor 314. Moreover,because the compressed air is rotating laterally within the cowl 710,particles entrained within the compressed air experience centrifugalforce causing the particles to contact the cowl 710. In an embodiment,the cowl 710 includes ridges 712 that increase a drag force on theparticles and help slow the axial movement of the particles.

The plurality of openings 720 are located toward an axially distal endof the cowl 710. In an embodiment, the openings 720 are axiallyelongated. The size, shape, and number of the openings 720 may be variedto bleed off a desired portion of the compressed air. For example, thenumber of openings 720 may be between approximately 10 and 100,preferably approximately 60. Each opening 720 is in fluid communicationwith a respective vortex chamber 740. As will be described in furtherdetail below, the opening 720 leads to an inlet of the vortex chamber740. The vortex chamber 740 creates an outer vortex that pulls solidparticles into the collection chamber 750 and an inner vortex that pullsclean air to an outlet of the vortex chamber 740.

The collection chamber 750 includes one or more hollow regions thatreceive particles from the vortex chambers 740. In an embodiment, thecollection chamber 750 is sealable. For example, the collection chamber750 includes one or more vents 754 that may be opened or closed. Thevents 754 are closed during operation of the gas turbine engine 300.Accordingly, the collection chamber 750 retains the collected particlesduring operation. Moreover, because the collection chamber 750 is notvented during operation, the collection chamber 750 does not cause aloss in flow. The collection chamber 750 is vented during a shutdown,cleaning, or startup operation. During a startup operation, venting viathe collection chamber 750 helps reduce backpressure on the compressor314.

FIGS. 8 and 9 illustrate further details of the cyclonic separator 700.FIG. 8 is an axial cross-sectional view of the cyclonic separator 700and one of the vortex chambers 740. FIG. 9 is transverse cross-sectionalview of the cyclonic separator 700. The opening 720 is in fluidcommunication with the vortex chamber 740 via a curved passage 722. Thecurved passage 722 causes an airflow 724 to bend, starting a cyclonicmotion. As best seen in FIG. 8, the curved passage 722 communicates witha first end of the cyclonic chamber through an outer wall 742 thatdefines the vortex chamber 740. The outer wall 742 has a generallyconical shape and extends longitudinally to an open second end 752. Acentrally located vortex finder 744 extends longitudinally from thefirst end of the vortex chamber 740. The vortex finder 744 defines anexit flowpath 748. The vortex finder 744 includes a cylindrical portionhaving a solid wall located adjacent the first end of the vortex chamber740 and a conical portion 746 having a perforated wall extendinglongitudinally from the cylindrical portion.

The second end 752 of the vortex chamber 740 extends in a radiallyproximal direction into the collection chamber 750. The second end 752is located near a radially proximal surface 756 of the collectionchamber 750. The vortex chamber 740 may also be angled laterally.

In operation, the airflow 724 of compressed air enters the opening 720and follows the curved passage 722 into the vortex chamber 740. Theouter wall 742 and the cylindrical portion of the vortex finder 744continue to bend the airflow 724 to form an outer vortex spiraling aboutthe vortex finder 744. As the airflow 724 reaches the conical portion746, solid particles entrained in the airflow 724 tend to move to theouter wall 742 due to centrifugal and drag forces. Clean air near thecenter of the vortex chamber 740 enters the vortex finder 744 via theperforations and via the inner vortex opening. The dirty air entrainingthe solid particles continues to move longitudinally and is dischargedvia the second end 752 into the collection chamber 750. The lateralangle of the vortex chambers 740 imparts a circular movement to the airwithin the collection chamber 750. The solid particles are drawn towardthe radially distal wall 758 of the collection chamber rather thanreentering the second end 752. The exit flowpath 748 provides a cleanairflow, for example, the first cleaned airflow 610.

The components of the gas turbine engine 300 may be manufactured usingan additive manufacturing (AM) process. AM encompasses variousmanufacturing and prototyping techniques known under a variety of names,including freeform fabrication, 3D printing, rapid prototyping/tooling,etc. AM techniques are capable of fabricating complex components from awide variety of materials. Generally, a freestanding object can befabricated from a computer aided design (CAD) model. A particular typeof AM process, direct metal laser melting (DMLM), uses an energy beam,for example, an electron beam or electromagnetic radiation such as alaser beam, to sinter or melt a powder material, creating a solidthree-dimensional object in which particles of the powder material arebonded together. AM may be particularly applicable for manufacturing,for example, the cyclonic separator 700, which includes multipleconcentric and coaxial subcomponents. In an aspect, the cyclonicseparator 700 may be fabricated in a layer-by-layer manner along thelongitudinal axis. The AM process may fabricate the cyclonic separator700 as an integrated structure.

This written description uses examples to disclose the invention,including the preferred embodiments, and also to enable any personskilled in the art to practice the invention, including making and usingany devices or systems and performing any incorporated methods. Thepatentable scope of the invention is defined by the claims, and mayinclude other examples that occur to those skilled in the art. Suchother examples are intended to be within the scope of the claims if theyhave structural elements that do not differ from the literal language ofthe claims, or if they include equivalent structural elements withinsubstantial differences from the literal language of the claims.Aspects from the various embodiments described, as well as other knownequivalents for each such aspect, can be mixed and matched by one ofordinary skill in the art to construct additional embodiments andtechniques in accordance with principles of this application.

1-15. (canceled)
 16. A gas turbine engine, comprising: a firstseparation device that receives ambient air including entrained solidparticles and removes at least 80 percent of the solid particles havinga mean particle diameter between 80 micrometers and 1000 micrometersfrom the ambient air; a compressor that receives the ambient air fromthe first separation device and generates compressed air; and a secondseparation device that receives compressed air from the compressorincluding entrained solid particles having a mean particle diameter lessthan 5 micrometers and removes at least 70 percent of the entrainedsolid particles from the compressed air.
 17. The gas turbine engine ofclaim 16, wherein the compressor pulverizes solid particles remaining inthe ambient air such that the mean particle diameter is less than 5micrometers.
 18. The gas turbine engine of claim 16, wherein the firstseparation device removes at least 80 percent of the solid particleshaving a mean particle diameter between 80 micrometers and 1000micrometers from the ambient air.
 19. The gas turbine engine of claim18, wherein the first separation device removes at least 95 percent ofthe solid particles having a mean particle diameter between 80micrometers and 1000 micrometers from the ambient air.
 20. The gasturbine engine of claim 16, wherein the second separation device removesat least 80 percent of the entrained solid particles having a meanparticle diameter less than 5 micrometers from the compressed air. 21.The gas turbine engine of claim 16, wherein the first separation deviceis a radial inlet particle separator.
 22. The gas turbine engine ofclaim 21, wherein the radial inlet particle separator includes aplurality of circumferential vanes extending in a radially proximaldirection along an inlet to a core of the gas turbine engine.
 23. Thegas turbine engine of claim 22, wherein the vanes are angled toward aforward air inlet of the gas turbine engine.
 24. The gas turbine engineof claim 16, wherein the second separation device is a multiple stageseparation system.
 25. The gas turbine engine of claim 16, wherein themultiple stage separation system includes a cyclonic separator and aclean air offtake downstream from the cyclonic separator.
 26. A methodof removing solid particles from an airflow in a gas turbine engineincluding a compressor and a combustor, the method comprising: receivingambient air including entrained solid particles; removing at least 80percent of the entrained solid particles having a mean particle diameterbetween 80 micrometers and 1000 micrometers from the ambient air beforethe compressor; compressing the ambient air in the compressor togenerate compressed air including entrained solid particles having amean particle diameter less than 5 micrometers; and removing at least 80percent of the entrained solid particles from the compressed air beforethe combustor.
 27. The method of claim 26, wherein compressing theambient air in the compressor includes pulverizing particles having aparticle diameter greater than 5 micrometers.
 28. The method of claim27, wherein the pulverizing increases a density of entrained solidparticles having a mean particle diameter less than 5 micrometers. 29.The method of claim 26, wherein removing at least 80 percent of theentrained solid particles from the compressed air before the combustorcomprises: bleeding at least a portion of the compressed air into asecondary airflow; and cleaning the secondary airflow with a cyclonicseparator.